We had an overnight stay in Lanzhou as a break to acclimatize for our train journey to Lhasa. It was worthwhile staying overnight as we were able to do last minute shopping and visit the park that overlooks Lanzhou city.
There are some good outdoor and camping stores in Lanzhou. We had a fabulous dinner at a tiny restaurant in a Hutong area.
Lanzhou is usually used as a travel hub. That's fair but it's worth kicking back and getting to know it.
IMO, it's biggest blessing is it's fairly large Muslim Hui-zu community. I think they largely influence the character of Lanzhou, which seems to be much more genuinely friendly and polite than many other places in China. They also make great food. Lanzhou is famous for it's beef and "La Mian" (lit. "pull noodles") but you can also get the Tibetan Mian Pian (squares instead of noodles), fresh bread-cakes and some great lamb there too. If you like cumin, green onions and a touch of peppers/chillies, you'll be in heaven. Try the Hui neighbourhoods around the mosques just north of the South Bus station for the best beef for only about 8 kuai in a steaming bowl of fresh noodles! I loved visiting the Buddhist temple complex north of the river, some friends at the university, drinking beer on the river and just wandering around chatting with people in between catching buses and trains for onward travel.